I live in an adobe house and don't open my windows much. The ash doesn't get into the house too badly except at the doors (the kitchen door, for example, is almost always open because the shade from the backyard cools the air), and vigilant sweeping keeps it pretty much under control. You should also bear in mind that I live in an area of very limited ashfall - my friends downhill in Baņos, at the foot of the volcano, have all but given up on computers until the eruption stops. The volumes of ash seen in Alaska due to the Mt. Redoubt eruption have been on the order of 100s of times larger than what I get.
Oh, and I get earthquakes, too. We had one this morning, which I'm shocked to find was a 6.9 epicentered in the jungle about 125 km away from me - it didn't feel anything like that strong - no structural damage or anything. The last time I was in a 6.1, walls fell. I'm quite confident, however, of the construction of the home I live in vis a vis earthquake stability - my walls are nearly 12" thick.
I get fungal/rot problems only during the peak of the wet season, and that's pretty much limited to powdery mildew, which is easy to keep in check. It's quite dusty, but most people grow tough xeric grasses in their yards to keep it down, and Datura and Epazote colonize everything, which tends to hold the top in fairly well, except when it gets really windy (which it does, especially when the seasons change over.) On very hot days, the main sport in this city seems to be "stalk the beer truck" - the local stores run out of cold "biggies" pretty fast - fyi beer comes in two sizes: regular 10 oz. small bottles, and large 28 oz'ers, which, at 75 cents a pop, are preferred.
You'd be surprised at how resistant Cortaderia is to this kind of environment - it's an ideal shelter plant for younger Agaves and Aloes. Of course, it also goes invasive really easily, so take my advice with a grain of salt.